Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
P010 Production and detoxification mechanisms of methylglyoxal in photosynthetic organisms: photosynthesis stimulated the production of methylglyoxal Ginga Shimakawa1 and Chikahiro Miyake2 1 Kobe University, Kobe, Japan 2 Graduate School of Agricultural Science, Kobe University, Kobe, Japan Methylglyoxal (MG) is produced in the equilibration reaction between dihydroxyacetone phosphate (DHAP) and glyceraldehydes 3-phosphate (GAP) catalyzed by triose phosphate isomerase (TPI) in the glycolysis. TPI also functions in the Calvin cycle of photosynthetic organisms. We tried to detect MG during photosynthesis in intact chloroplasts isolated from plants leaves. Orthophenylene diamine-derived MG was analyzed by HPLC-system. In the Calvin cycle of chloroplasts, 3-phosphoglycerate (3-PGA) is metabolized to GAP catalyzed by PGA kinase and GAP dehydrogenase sequentially, and GAP was equilibrated with DHAP. The addition of 3-PGA to the illuminated chloroplasts induced photosynthetic O2 evolution and MG production. The production rate of MG increased with the increases in light intensity and 3-PGA concentration. These results indicated that the production of MG is inevitable in the photosynthesis and the stimulation of photosynthesis enhances the MG toxicity. We furthermore sought glyoxalase system in the origin of oxygenic photosynthetic organisms, cyanobacteria. Cyanobacteria are the prokaryotes, that is, photosynthesis and respiration occur in the same compartment of the cytosol. Therefore, cyanobacteria are exposed to the much stronger sugar-toxicity, compared to higher plants. We found the gene, SyGLX1 in Synechocystis sp. PCC6803 (S. 6803), homologous to AtGLX1 (At1g11840) in Arabidopsis thaliana and SyGLX2, homologous to AtGLX2 (At3g10850). Both GLX1 and GLX2 showed the activities of glyoxlase systems. We wild report the detailed analysis of the detoxification mechanisms of sugar-derived RCs in cyanobacteria.